There are many situations in which it is useful to know whether or not a predetermined amount of pressure has been applied to a surface. One such situation is when a base plate of a structure adapted to support an item such as a hook, a soap dish, or a basket is to be adhered to a surface by a layer of stretch release pressure sensitive adhesive. The layer of stretch release pressure sensitive adhesive can firmly adhere a surface of the base plate to a surface (typically a vertical surface), and after the item is no longer needed, can be stretched from between the base plate and that surface to release its adhesion to the base plate and that surface. Several assemblies including such structures are commercially available from 3M Company, St. Paul, Minn., including an assembly commercially designated “Command™ Adhesive large hook #17003”. It is important in adhering such a structure to a surface that a suitable amount of pressure is applied for a suitable amount of time to press the adhesive against the surface to which the structure is to be adhered (e.g., at least about 10 pounds per square inch of pressure or 0.7 kilograms per square centimeter should be applied for a few seconds) so that the adhesive will completely wet out that surface together with a surface of the base plate that will typically be wet out at a somewhat lower pressure (i.e., the surface to which the structure is to be adhered typically is rougher and harder to wet than the surface of the base plate). If the adhesive does not fully wet out the surface to which the structure is to be adhered, the bond strength of the adhesive with that surface can be reduced by over 50 percent. Persons applying the pressure typically do so for an adequate amount of time (i.e., about 5 to 10 seconds), however, adequate pressure is sometimes not applied. This is particularly so on base plates that are adapted to support large items such as jumbo hooks, which base plates have large surface areas that must be adhered to the surface by a large area of pressure sensitive adhesive (e.g., 4 square inches of adhesive) that requires a large application force (e.g., over about 40 pounds) to wet out that surface so that the full bond strength of the pressure sensitive adhesive can be developed. The pressure required to develop full bond strength of that large area of pressure sensitive adhesive can be applied by sequentially pressing on top, bottom and side portions of the base plate, however, the person applying such pressure is never quite sure that enough pressure has been applied to each of those portions. For example, the bottom and side portions may have had a sufficient amount of pressure applied, but insufficient pressure may have been applied to the top portion.
Another situation in which it is useful to know whether or not at least a predetermined amount of pressure or force has been applied to a surface is when an object is being shipped by commercial carrier, and the application of pressure or force above a predetermined amount during shipment could cause damage to that object.